1. Technical Field
The present invention relates to digital watermarking of data, including audio, video, and multimedia data. Specifically, the invention relates to embedding a watermark signal into digital audio data.
2. Description of the Related Art
The proliferation of digitized media such as image, video and multimedia is creating a need for security system which facilitates the identification of the source of the material. Particularly, the internet is increasingly used for transmitting recorded music in a digitized format. Content providers, i.e., owners of such recorded music in digital form, have a need to embed into multimedia data a predetermined mark which can subsequently be detected by software and/or hardware devices for purposes of authenticating copyright ownership, control and management of the multimedia data. Digital watermarking has been developed as a technique for embedding an identifiable data into multimedia data.
Conventionally, a watermark signal used for watermarking audio signal has been relatively simple signals such as a sequence of code symbols because, unlike image or video, inserting a large watermark signal would affect original audio perceptibility. Therefore, a watermarking technique employing a large image as a watermark signal has been proposed. However, prior arts watermarking techniques involving an image watermark are susceptible to unauthorized removal of watermarks, thereby making hard to trace the origin of a copyright protected material.